The present invention relates to a process for preparing piperazine of the formula I
by reacting diethanolamine (DEOA) of the formula II
with ammonia in the presence of hydrogen and a supported, metal-containing catalyst.
Piperazine is used inter alia as an intermediate in the production of fuel additives (U.S. Pat. No. 3,275,554 A; DE 21 25 039 A and DE 36 11 230 A), surfactants, medicaments and crop protection compositions, hardeners for epoxy resins, catalysts for polyurethanes, intermediates for producing quaternary ammonium compounds, plasticizers, corrosion inhibitors, synthetic resins, ion exchangers, textile auxiliaries, dyes, vulcanization accelerators and/or emulsifiers.
WO 03/051508 A1 (Huntsman Petrochemical Corp.) relates to processes for the amination of alcohols using specific Cu/Ni/Zr/Sn-containing catalysts which, in a further embodiment, comprise Cr instead of Zr (see page 4, lines 10-16). The catalysts described in this WO application comprise no aluminum oxide and no cobalt.
WO 2008/006750 A1 (BASF AG) relates to certain Pb, Bi, Sn, Sb and/or In-doped, zirconium dioxide-, copper-, nickel- and cobalt-containing catalysts and their use in processes for preparing an amine by reacting a primary or secondary alcohol, aldehyde and/or ketone with hydrogen and ammonia, a primary or secondary amine. Aluminum oxide supports are not taught.
WO 2009/080507 A1 (BASF SE) describes certain Sn and Co-doped, zirconium dioxide-, copper- and nickel-containing catalysts and their use in processes for preparing an amine by reacting a primary or secondary alcohol, aldehyde and/or ketone with hydrogen and ammonia, a primary or secondary amine. Aluminum oxide supports are not taught.
WO 2009/080506 A1 (BASF SE) describes certain Pb, Bi, Sn, Mo, Sb and/or P-doped, zirconium dioxide-, nickel- and iron-containing catalysts and their use in processes for preparing an amine by reacting a primary or secondary alcohol, aldehyde and/or ketone with hydrogen and ammonia, a primary or secondary amine. Aluminum oxide supports are not taught. Preferably, the catalysts comprise no Cu and no Co.
WO 2009/080508 A1 (BASF SE) teaches certain Pb, Bi, Sn and/or Sb-doped, zirconium dioxide-, copper-, nickel-, cobalt- and iron-containing catalysts and their use in processes for preparing an amine by reacting a primary or secondary alcohol, aldehyde and/or ketone with hydrogen and ammonia, a primary or secondary amine. Aluminum oxide supports are not taught.
WO 2011/067199 A1 (BASF SE) relates to certain aluminum oxide-, copper-, nickel-, cobalt- and tin-containing catalysts and their use in processes for preparing an amine from a primary or secondary alcohol, aldehyde and/or ketone. The preparation of piperazine from DEOA and ammonia is mentioned generally on page 22, line 28.
WO 2011/157710 A1 (BASF SE) describes the preparation of certain cyclic tertiary methylamines, where an aminoalcohol from the group 1,4-aminobutanol, 1,5-aminopentanol, aminodiglycol (ADG) or aminoethylethanolamine, is reacted with methanol at elevated temperature in the presence of a copper-containing heterogeneous catalyst in the liquid phase.
WO 2012/049101 A1 (BASF SE) relates to a process for preparing certain cyclic tertiary amines by reacting an aminoalcohol from the group 1,4-aminobutanol, 1,5-aminopentanol, aminodiglycol (ADG) or aminoethylethanolamine with a certain primary or secondary alcohol at elevated temperature in the presence of a copper-containing heterogeneous catalyst in the liquid phase.
CN 102 304 101 A (Shaoxing Xingxin Chem. Co., Ltd.) relates to the simultaneous preparation of piperazine and N-alkylpiperazines by reacting N-hydroxyethyl-1,2-ethanediamine with primary C1-7-alcohols in the presence of metallic catalysts.
DE 198 59 776 A1 (BASF AG) relates to certain amination processes using catalyst moldings which comprise oxygen-containing compounds of titanium and of copper and metallic copper.